When Schiit says spdif is better than USB, I think they are talking about ultimate performance, not using some rubbish spdif output on your computer/laptop.

Schiit has also never said that Optical is better than USB. When they say 'spdif', we know they are actually talking about coaxial, because coaxial has lower jitter and sounds better compared to optical.

If your only source is an iMac or laptop, then sure, you will probably find async USB better than the cheapo optical or coaxial output. But put your USB laptop up against a good transport or audiophile network streamer, then I believe spdif will come out on top.

See above: "There are 'small truths' in favor of each of these interfaces (optical eliminates all electrical sources of distortion through ground; coax has greater bandwidth than optical; async USB tends to have lower jitter than all but very expensive S/PDIF implementations)...."

....The particular implementation is going to determine in each case how the given interface will sound. When we're going to have lots of people in two-three weeks using all the different Bifrost interfaces with lots of different associated equipment, what's the use now of speculating, much less making definitive statements? You'll have people who can tell you what sounds best in their own setups, and some of those will match yours fairly well. For my part, I plan to try the Bifrost using optical out from my MacBook Pro; USB through Musical Fidelity V-Link to coax; and USB direct. I'll also run coax from my Oppo BDP-83 to the Bifrost. I'll see which of those sounds best, and add my voice to the others here who'll be reporting back on their own experiences.

I can tell you that my MacBook Pro USB through the V-Link then coax to my current DAC (Theta Pro Basic II) sounds better than the BDP-83 through coax.

I have to say, Schiit has done a really good job with their product line for people like me - strictly digital listeners who want an amazing setup for under $1000.

I realize a lot of audiophiles around here don't hold onto equipment for a long time but I just don't see myself getting a pair of cans that require something more powerful than the Bifrost and the Valhella/Asgard.

I am not surprised. Despite every claim about X>Y>Z standard every piece of gear I try (from $30 to $3000) yields a different result as to which is the best. I can draw no conclusion other than it's all in the implementation and execution of the chosen standard. There might be a theoretical answer but practical listening makes it seem more complicated to me.

Exactly. Implementation is going to trump "theory" every time in audio. I put "theory" in quotes because so often some small truth gets unjustifiably enlarged to an absolute, and in audio the truths tend to be quite small, not so widely applicable as to cover the entirety of what's going on in any given piece of equipment.

I've got a Bifrost on order and will be very interested to hear the S/PDIF optical, coaxial, and USB inputs. There are "small truths" in favor of each of these interfaces (optical eliminates all electrical sources of distortion through ground; coax has greater bandwidth than optical; async USB tends to have lower jitter than all but very expensive S/PDIF implementations), but none large enough to say that one absolutely will sound better than the others in my system. I will have to wait and listen to find out.

I look forward to your impressions. I was wondering if you could go a bit into 'bandwidth'. It's been stated what the theoretical bandwidth hierarchy is but how does it differ from transfer rate and throughput? I assume we are talking about the width of a river not the flow of the current. Especially when we are talking a digital stream rather than analog. I think many of us have the wrong mental picture of binary 1's and 0's flowing linearly through a pipe.

Also, if bandwidth is a real consideration then how would usb>spdif converters overcome the initial bottleneck at the usb port? Wouldn't they just be sending a pretty usb signal or something reconstructed rather than true spdif passed through from the source?

My I-mac's about 5 years old; can this vintage machine output S/PDIF via the headphone output? And what needs be done as to settings, and cables? I plan to use my Bifrost out of my CD player for now, but would also like to try computer audio. Any help is appreciated.

"An often-overlooked cause of jitter is bandwidth limiting of the digital signal. Quoting from the Rémy Fourré Stereophile article 'Jitter and the Digital Interface' published in the October, 1993 issue: 'A word about optical links. Still using the example above with digital signals A and B, a low-pass filter at 5MHz-typical of TosLink-causes a time difference of 121ps. A 6MHz low-pass filter causes a time difference of 33ps. For adequate performance, optical links must have a bandwidth of 9MHz minimum. To operate at 48kHz and have a 15% margin for speed adjustments, the interface bandwidth must be at least 11MHz.'"

Note re your question about USB speed that although the actual transfer speed won't be up to the 2.0 spec of 480Mbps, still some considerable fraction of that is more than fast enough to keep a buffer full that's being emptied at a max rate of 192khz (the sample rate at which the data's being clocked out of the buffer into the DAC conversion circuitry) x 24 (the bit depth). Rounding for ease of calculation, call it 200 samples per second x 25 bits, or 5Mbps. (Hope I've got the math right here - been 40 years since high school calculus, folks!)

Note also this additional discussion from the link above:

"When constructed from very high purity quartz, TOSLINK interconnects can exhibit a very wide bandwidth - 10MHz is not uncommon in practice. Compare this with the performance of a typical plastic conductor fiber optic cable that reaches its limitations at a mere 5MHz to 6MHz."

Now is this info reliable? Heck if I know. I was just throwing out stuff you hear about the various interfaces to caution that no one should rely on these supposed truths, but rather we should all actually listen. I will say, though, that Mike Moffat, designer of the Bifrost, did get behind a high-quality S/PDIF optical interface back in his Theta Digital days. It was called the Laser Linque, and it sounded very, very good. (Heard it at a friend's audio store, never owned one myself.) So in principle there's nothing to say a sufficiently high quality optical input can't be as good as or better than coax. But once again (I'll repeat, because it bears repeating), it's the implementation, revealed by listening, that tells you which interface is being most effectively utilized in a particular DAC in your own system.

I have to say, Schiit has done a really good job with their product line for people like me - strictly digital listeners who want an amazing setup for under $1000.

I realize a lot of audiophiles around here don't hold onto equipment for a long time but I just don't see myself getting a pair of cans that require something more powerful than the Bifrost and the Valhella/Asgard.

The new transformers are here, a little later than expected. That said, it looks like we'll start shipping Bifrosts at the end of the month as planned--it'll just be a little slow at first. As usual, we'll be shipping earliest orders first, so I'll have to ask for your patience if you ordered recently. It should take only a couple of weeks to clear all the pre-orders.